JP3347743B2 - Heating system for tanks storing liquid products - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to improving the heating of liquid products, in particular petroleum and its derivatives, and relates to undesirable materials (concentrations) that normally accumulate at the bottom of liquid storage tanks. High residue, sludge, water, sand, etc.).

BACKGROUND OF THE INVENTION It is known to provide a floating roof in a tank containing a relatively volatile liquid to prevent the formation of gas spaces in the tank. When the floating roof of such a tank for storing liquid products is low, it is not generally possible to use the customary systems normally used for heating liquid products. These basically depend on various factors such as, for example, the type of product, the amount stored, the temperature to be reached, and the heating time.

The present invention is a tank with a low floating roof as described in International Patent Application No.PCT / BR97 / 00022, which can be used for such a low working height, but for conventional tanks It is an object to provide a tank with an individual heating system that can also be used.

Prior art Storage tanks are widely used in the petroleum industry and are essential for the functioning of work facilities. They are used, for example, for storing crude oils, intermediate products and finished products.

The heating sources used include heated liquids, pressurized steam, electrical energy or other less conventional sources.

The coil through which the hot fluid passes is among the most common methods of heating the tank. In normal use, they are generally at a distance of 0.80 meters from the level of the tank floor. It has significant wasted space. Laterally mounted heat exchangers have also been used.

Inventor's International Patent Application No. PCT / BR97 / 00022 relates to a new type of tank floor to which the heating system of the present invention is particularly suitable. The international patent application proposes the use of a floor whose center is located at a height lower than the height of the edge. The residue to be discharged collects in the central area at the bottom of the tank.

By installing this new type of floor, the drainage of the tank can be lowered to a position much closer to the floor than previously achieved, since the drainage of unwanted liquids is better. As a result, if the product needs to be heated in a tank of this type, a new problem is that it is necessary to have a heating system that can be accommodated in a small space (minimum operating height) of the order of 10 cm. Occurs. However, this type of heating system is not known in the prior art.

The minimum working height is the minimum height above the tank floor,
At that height the floating roof needs to be held during work. In current storage tanks, especially large capacity tanks, this minimum working height is on the order of about 1 meter 40 cm.

The maintenance height is the height at which the floating roof needs to be held in the maintenance mode so that personnel can enter the interior of the tank for performing maintenance work. This is higher than the minimum working height.

DE-A-2 534 380 discloses a tank having heating pipes directly above the floor of the tank and comprising a plurality of radially extending pipes, the radially extending pipes comprising at least one circumferentially arcuate outer pipe and Connected and arranged such that adjacent ones of said radial pipes are interconnected near the center of the tank floor.

SUMMARY OF THE INVENTION The present invention solves the aforementioned problems and provides an improved product storage tank that saves time and reduces operating costs.

A heating system according to the invention is defined in claim 1. The present invention also provides a liquid storage tank including such a heating system.

The flow of the heating fluid, preferably steam, is concentrated (towards the center) or spreads (towards the periphery) principally radial tubes
tubes). All tubes carry the heating fluid and connect the central inner arc to the outer arc. Each arc may itself form a ring, or may be a series of arcs that may or may not form a complete ring. An explanation can be made by analogy between this assembly and the foil. In that case, the rim of the foil corresponds to the outer ring (perimeter) and the hub of the foil corresponds to the inner ring. The spokes of the foil correspond to the radial tubes. Thus, the system comprises a first tube, generally in the form of an outer arc, and a second tube, generally in the form of an inner arc, wherein both tubes are interconnected by a primary radial tube; A plurality of branches emerge from the primary radial tube, and the branches also take a radial geometry to form secondary radial tubes, wherein the secondary tubes are as described above. Extends to the outer arc. The system is supported by supports fixed to these tubes and is simply stationary without being fixed, for example, welded to the tank floor. Most of the tubes in the system are sloped downward to prevent the formation of water hammers and save energy (as described below).

Preferably, the floor of the tank has its center height below the edge height. Thus, the residue that is desirably discharged collects in the central area at the bottom. Also, in this case, a ramp-type drainage channel is used that starts at the center of the bottom of the tank and extends toward the edge. The ramp is angled sufficiently to facilitate discharging undesired material to the outside of the tank.

However, the invention can alternatively be used on tank floors with outlets around the tank to provide this type of tank with a heating system.

BRIEF DESCRIPTION OF THE DRAWINGS The characteristics of the present invention will be better understood, based on the detailed description provided hereinafter by way of example only, in combination with the following drawings, which are an integral part of the specification.

FIG. 1 shows a partial radial type for a product storage tank with an inverted floor (which is upwardly convex) as described in PCT / BR97 / 00022. FIG. 2 is a plan view of a heating system according to an embodiment of the present invention. FIG. 2 is a side view of a heating system for an oil storage tank having an inverted bottom, and FIG. FIG. 3 is a side view of another conventional heating system for a petroleum storage tank with a bottom, showing a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION The heating system shown in the drawings uses steam which may or may not be overheated as a heating medium.

FIG. 1 shows a storage tank 1 with a heating system according to the invention. The perimeter represents the side wall of the tank and the circle represents the boundary of the tank floor. A first arcuate tube 2, generally in the form of an outer arc, defining an outer ring portion through which the heating fluid or steam enters (acting as a hot heating fluid or steam distributor); There is a second arcuate tube 3 which is generally in the form of an inner arc and forms an inner ring part (cold heating fluid or condensate receiving device) through which steam exits. The heating system shown covers just under a quarter of the floor area of the tank.

Five primary radial tubes 4 are shown. FIG.
Also shows four secondary radial tubes 5,
Each of the secondary radial tubes is connected by a small tube segment at the midpoint of the respective primary radial tube. These midpoints are preferably closer to the arc of the inner tube 3 than to the arc of the outer tube 2. Also, there is at least one small channel 6 on the floor of the tank, which is a discharge channel for discharging liquid product from the tank, this small channel forming part of the present invention. It does not do. Each such small channel 6 extends from the center of the tank to the edge of the tank and is sloped to allow for drainage.

FIG. 2 is a side view of a second embodiment of the invention, wherein the radial tube covers more than a quarter (almost a semicircle) of the circular area of the tank. This embodiment also applies to storage tanks with inverted floors (conically upwards) such as that shown in FIG. The support 8 for the tubes 4 and 5 is on the floor 7 of the tank. It can be seen that this drawing does not show the secondary radial tube 5. The support 8 has a substantially equal length, which means that the tubes 4 and 5 maintain the same vertical distance from the tank floor 7. The slope of the tank floor 7 is sufficient to facilitate the discharge of unwanted liquid from the edge of the tank toward the center of the tank. FIG. 2 also shows a radially extending discharge channel floor 9 in the tank floor 7, where the support 10 provides
An outer tube 11 for the condensate of the heating system is located. The tops of the supports 8 and 10 are fixed to the tubes 4 and 11, respectively, and the bottoms of the supports can be placed on the tank floor 7 or the channel floor 9 respectively. Each support may be a chamfered notched block welded to the tube.

FIG. 3 shows a third embodiment of the invention applied to a storage tank with a conventional floor (the edge is lower than the center). The heating system is mounted as low as possible on the floor 12 of the tank and is fixed only to a support 8 of approximately equal length.
This mounting is performed in the same manner as the embodiment shown in FIG. However, in contrast to the inverted floor,
There is at least one generally radial type inlet tube 13 through which the heated steam enters. The inlet tube, like other tubes of this type, is supported by a support 14 that decreases in length as it approaches the center of the tank. The slope of the tank floor 12 is sufficient to facilitate the drainage of unwanted liquid from the center to the edge of the storage tank 1.

Depending on the shape of the bottom, i.e. inverted or conventional, the inner arc becomes a receiving device or a distributing device, i.e. the steam passes through the outer arc tube 2 or the inner one. It can be entered via an arc tube 3. In any case, the primary radial tube 4, the secondary radial tube 5, the inlet tube 1
3, and the outlet tubes 11 are all inclined downward with respect to the inclination of the tank floor. The non-inclined part of the system is a non-radial type branch connected to the rings 2 and 3 and the secondary tube 5, which is very short. As a result, the flow of steam in the system is constantly falling thereafter, making it easier for condensate to come out. As a result, the system has no condensate build-up that promotes the water hammer. Assuming that there is no water hammer phenomenon, instead of using a condensate discharge valve at the discharge of the heating device, a thermostatic controller may be used to make available some of the condensate energy. This means
Depending on the characteristics of the steam used (eg superheat)
% Energy savings, which is an important advantage of the present invention.

The number of radial tubes can vary as a function of the space at the bottom of the tank. FIG. 1 shows the respective tubes 2 and 3 of the outer arc portion and the inner arc portion, and also shows that the radial tube occupies almost one quarter of the circle of the tank, ie only a sector of the circle. In FIG.
These tubes 2 and 3 are arc-shaped, but may have other shapes in plan view, for example polygons.

The system may or may not be divided into parts. If divided into parts, each constitutes an individual heating device. Various independent sectors are obtained. If not, the rings are continuous. Both possibilities fall within the scope of the invention. Condensate discharge is concentrated in a larger diameter tube. Thus, for example, in FIG. 2, the diameter of the surrounding tube 2 is 10.16 cm (4
inches) and that of the central tube 3 can be 15.24 centimeters (6 inches). In FIG. 3, these preferred values are reversed, ie, tube 2 is larger than tube 3. The arrangement of the secondary radial tubes 5 shown in FIG. 1 makes full use of the surface area of the tank floor and ensures that the heating is distributed evenly at all positions of the tank floor.

The difference in height between the center and the edge of the bottom of the storage tank is to facilitate the flow of undesired liquid towards the lowest part of the storage tank floor. Most of the heating tubes used in the present invention are radial, i.e., they extend in the same direction as the undesired material movement, so that there is no significant obstacle to such movement. This is an advantage of the present invention. In the case of coils, the movement is difficult because a portion of the tube is always transverse to the path in which the unwanted material is moving.

A further advantage of the present invention is that the radial tubes can be very close to each other, so that the radial system has a much higher heating capability compared to the coil form. Instead of heating the entire tank, the tank can be divided into blocks and heated. It is therefore possible to prevent the condensate from leaving at high temperatures. Condensate can exit at a controlled temperature, saving energy.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-97379 (JP, A) JP-A-59-209581 (JP, A) JP-A-60-68289 (JP, A) 109121 (JP, U) Japanese Utility Model Showa 55-90586 (JP, U) Japanese Utility Model Showa 51-83007 (JP, U) Japanese Utility Model Showa 51-83008 (JP, U) (58) Field surveyed (Int. ⁷ , DB name) B65D 88/74

Claims (6)

(57) [Claims] 1. A heating system for a tank for storing a liquid product, comprising: a) a first tube (2) extending generally in an outer arc.
And a second tube (4) extending generally through the inner arc (3); b) a primary radial tube (4) connecting said first and second arc tubes (2) and (3). C) a plurality of branches forming a secondary radial tube (5) exiting said primary radial tube and then extending radially to said outer arcuate tube (2); d) a support (8) fixed to the tube and stationary on the floor (7, 12) of the tank, the tank having a height at the center of the floor (7) at the edge. Lower than the height, the discharge channel (6) is at the tank floor (7)
At least one outlet tube (11) fixed to said tube and stationary on said floor (9) of said flow path (6). The second tube (3), to which a support (10) is attached;
A heating system for a tank for storing liquid products, characterized in that there is at least one outlet tube (11) for condensate from. 2. A heating system for a tank for storing a liquid product, comprising: a) a first tube (2) extending generally in an outer arc.
And a second tube (4) extending generally through the inner arc (3); b) a primary radial tube (4) connecting said first and second arc tubes (2) and (3). C) a plurality of branches forming a secondary radial tube (5) exiting said primary radial tube and then extending radially to said outer arcuate tube (2); d) a support (8) fixed to the tube and resting on the tank floor (7, 12), the tank floor (12) having an edge at a height in the center of the tank. Underneath there is at least one generally radial inlet tube (13) through which steam enters said second tube (3), said inlet tube (13) being fixed to said tube. And supported by a support (14) which is stationary on the tank floor (12). Heating system characterized in that it is. 3. The heating system according to claim 1, wherein the primary and secondary tubes occupy at least one sector of a circle. 4. The heating system according to claim 1, wherein the heating is performed by steam. 5. A tank for storing a liquid product comprising the heating system according to claim 1. 6. The tank according to claim 5, wherein the support is stationary without being fixed to the floor of the tank.